1. JLEIC Collider Rings’ Geometry Options (II)
Fanglei Lin, Vasiliy Morozov

2. Exploration of Collider Ring Geometry
Option
Condition
Circ.
Figure-8 crossing angle
Arc length
Straight length
IP to crossing angle
To CEBAF m
degree ft 1
Current spin rotator1 + current CCB + straight. CCB replaces the second dipole set in spin rotator.
2343 69
971
200 50 2
Current spin rotator, no CCB2.
2323
795
367
130 30
2.1
Current spin rotator, no CCB.
2232
77.4
818
298
100 3
New spin rotator3 + current CCB + straight. (see more info about new spin rotator in slide 6)
2327
67.8
986
178 40 20 4
New spin rotator, no CCB.
2273
825
312
120 5
New spin rotator + current CCB + straight.
2277 72
998
141
111 6
2186
76.2
848
245 70
Presented in JLEIC RD meeting on April 5, 2018

3. Presented in JLEIC RD meeting on April 5, 2018
1 (orange)
2 (green)
3 (blue)
4 (cyan)
5 (magenta)
6 (dark green)
2.154 km, 367ft to CEBAF
Option 2.1
Option 6 and 2.1 (no CCB) are promising, but need nonlinear dynamic study.
Option with CCB may deserve more exploration.
Presented in JLEIC RD meeting on April 5, 2018

4. Exploration of Collider Ring Geometry
Option
Condition
Circ.
Figure-8 crossing angle
Arc length
Straight length
IP to crossing point
To CEBAF m
degree ft 1
Current spin rotator1 + current CCB + straight. CCB replaces the second dipole set in spin rotator.
2343 69
971
200 50 2
Current spin rotator, no CCB2.
2323
795
367
130 30
2.1
Current spin rotator, no CCB.
2230
77.4
823
292 90
221
7.2
CCB in the current spin rotator
2301 72
955
196 45 62 3
New spin rotator3 + current CCB + straight.
2327
67.8
986
178 40 20 4
New spin rotator, no CCB.
2273
825
312
100
120 5
New spin rotator + current CCB + straight.
2277
998
141
111 6
2186
76.2
848
245 70
298
8.1 (~ 3)
New spin rotator + CCB
2321
68.2
974
186
8.2 (~ 6)
New spin rotator, no CCB
2212
76.6
860
246

5. 2.1 (green)
7.2 (blue)

6. Spin Rotator and CCB e- e- Spin rotator CCB Note that
The current spin rotator and CCB designs have strong quadrupole strengths. Therefore, the total length of two sections is about 170m. The total length will be extended if we consider to lower the strengths by lengthening those quadrupoles.

7. Combined Spin Rotator and CCB (v7.2)
Dipole set, total bending angle 8.8
Dipole set, total bending angle 4.4
1st solenoid
2nd solenoid
Crab cavities
164.6 m e-
* Maximum quad strengths < 19 Tm at 10 GeV

8. Electron Ring v2.1 No CCBs, global chromaticity compensation only
Maximum normal conducting quad strength < 19 T/m at 10 GeV
Maximum sextupole strength ~ 738 T/m2 at 10 GeV, with pole tip field of 1.32 T at 6cm radius (trying to reduce chromaticities)
Touschek lifetime 20h at 5 GeV from MADX
(-4,+3) at 5 GeV
(-2,+1.5)  at 10 GeV

9. New Spin Rotator w/ Dogleg
4.4
11 m
7 m
x : radial field
y : vertical field
z : longitudinal field
From Anatoly’s team

10. New Spin Rotator Optics
1st two dipoles
bend vertically
2nd two dipoles
bend vertically
1st sol.
2nd sol.
Decoupling + horizontal bending dipole(s)

11. Electron Ring w/ New Spin Rotator
Doglegs are not needed in the ion collider ring.
Minimum vertical space of 2.4 m, between two beam centers, is required.
New spin rotator has no significant reduction in both space and integral of solenoid fields.
The last horizontal bending dipole(s)
can be implemented as an SBCC structure if CCB is considered for a local chromaticity compensation, v8.1.
can be a simple DBA lattice if CCB is not considered in the optics design, v8.2.

12. Comments
Options 1, 2, 2.1, 3, 4, 5 and 6 have the same arc FODO dipole radius of m and arc bending radius of m. They have similar equilibrium emittances of um at 5 GeV.
Option 7.2 has the arc FODO dipole radius of 96.9 m and arc bending radius of m. The equilibrium emittance is 52 um at 5 GeV
Options 8.1 and 8.2 have the same arc FODO dipole radius of 98.2 m and arc bending radius of m. They should have similar equilibrium emittances to the baseline design.

13. Other New Spin Rotator Optics (I)
1st dipole set, net bending angle 4.4 vertically
~0.7 m long vertically, ~40m long longitudinally
0.7 m

14. Other New Spin Rotator Optics (II)
1st dipole set, total bending angle 4.4 vertically
~0.75 m long vertically, ~20m long longitudinally
0.75 m

15. Thank You for Your Attention !